In a conventional semiconductor device, in order to protect a sensor IC and so on against an external environment such as dust, humidity, impact or the like, an injection molding is performed with ceramic material for air-tight sealing, with epoxy resin for resin sealing, or the like. Hereinafter, a vehicle speed sensor is taken as an example of resin moldings. Detecting precision of the vehicle speed sensor is largely influenced due to even slight fluctuation in a distance between a case surface and a detecting surface of the sensor IC. Therefore, requirements have lead to holding the sensor IC more accurately at a given position.
In general, if the sensor IC is sealed in resin under the condition that the sensor IC has been just located in the case, the sensor IC may be displaced from the given position. Therefore, performance of the semiconductor device may be deteriorated. In light of foregoing, a holding member has been conventionally applied for holding the sensor IC at an appropriate position inside the case, whereby the sensor IC is prevented from being displaced. The holding member is generally attached to a hole at a die surrounding the sensor IC, such that the holding member can hold the sensor IC at the given position. Resin is then injected into the die and molded therein. Accordingly, the sensor IC is sealed in the resin while the holding member retracts. In this case, the holding member should smoothly retracts from the case. For example, if the holding member is adjusted to move back from the case before charging a cavity with the molten resin, the sensor IC may displace due to flow of the molten resin. On the other hand, if the holding member is adjusted to move back from the case after charging the cavity with the molten resin, i.e., after the solidification of the resin, the resin does not reach holes at the holding member and a clearance between the resin and the holding member may be unnecessarily defined. This may cause deterioration of air tightness.
According to Japanese Patent Laid-Open Publication No. 1997-38982, resin is injected into a case while a held member is located inside the case and held by a holding member. The holding member can be moved back and forth relative to the case. This reference discloses a method of insert-molding the held member while the holding member is moved back from the case before charging the case with the resin or after thereof. According to the method of insert-molding the held member, a surface of the holding member in contact with the resin is heated by a heating device (a heating means). At least the holding member surface is heated up to a temperature higher than a surface of resin in contact with an inner surface of the case. Further, according to the method of insert-molding the held member, the resin only at the holding member is heated and molten by the heating device, and the holding member is moved back from the case. Therefore, it can effectively prevent the held member from displacing and avoid deterioration of airtightness.
However, the above-described method of insert-molding the held member requires the heating device and the holding device individually. Further, in order to heat the surface of the holding member in contact with the resin at a higher temperature than the surface of the resin in contact with the case, the heating device is required to be controlled appropriately.
Further, there may be a case that a main body and a flange portion are molded with a secondarily molding resin. The main body is molded for holding the case molded as described above. The flange portion is molded to laterally extend from the main body and is provided with an attaching hole.
A need exists for providing a holding structure capable of holding a held member such as a sensor IC at a given position when the held member is sealed in resin, and for providing a molding provided with the above-described holding structure. The holding structure can hold the held member at the given position with less manufacturing cost and power.